Duality is embedded in string notation as group theoretic structure (commutativity, associativity, arity), as absence of parallelism in both expressions and processes, as the semantics/syntax barrier, as forced representation of both relevant and irrelevant expressions, and as the Exclusion of the active agent (the mathematician) from the Notation.
(APAs) are known to possess great potential in supporting learning because of their ability to simulate a real classroom learning environment.